The detection of an operating state of a vehicle, in particular whether a trailer is coupled, or not, to a (commercial) vehicle, e.g., to a truck, is typically carried out or queried in the prior art via a CAN connection between the vehicle and the trailer or via a corresponding CAN signal. Vehicles and trailers also exist, however, that do not have such a CAN connection. It is also possible that the CAN connection is defective or either only the vehicle or the trailer has a CAN connection such that a status query of the vehicle cannot be carried out via the CAN connection.
It would therefore be desirable, in addition to or instead of the status query via a CAN connection, to provide a method and a device, which provide for the detection of the operating state of a vehicle, specifically the state of the vehicle in which a trailer (trailer mode) is attached, or in which a trailer is not attached (solo mode). A plurality of methods for this purpose are known from the prior art.
For example, a method for checking a vehicle/system by way of a control unit is described in the document DE 42 00 302 C2. The control unit comprises a pressure line, which is connected via a coupling point to a pressure line of a further system, e.g., of a trailer. A state of the system is determined by evaluation of the pressure in the pressure line.
In addition, it is known from the document DE 197 44 066 B4 to use a method for the detection of a trailer with respect to a vehicle, in which the control pressure going to the trailer is detected in such a way that a pressure build-up-characterizing variable is determined from a pressure signal and is evaluated.
Document DE 199 55 798 A1 describes a trailer detection for a combination of towing vehicle having a hydraulic brake system and a trailer having a pneumatic brake system, wherein the trailer is attached to the towing vehicle. For the detection as to whether a trailer is actually attached to the towing vehicle, the temporal behavior of the pressure in a pneumatic space, which is closed with respect to the atmosphere, is determined.
The patent application DE 33 02 236 A1 also describes a test device for a pressure change in a compressed-air system, in particular in a multi-circuit brake system. In addition, a method for testing a brake system of a vehicle in the static mode is known from document DE 40 39 957 A1.
The methods and devices known from the prior art have the disadvantage that they can be used only under certain conditions or prerequisites, specifically only when, e.g., a special brake system or a particular valve is available for use.
In this regard, the problem addressed by the invention is that of providing an improved method and an improved device for detecting an operating state of a vehicle, in particular a state of a vehicle with or without a trailer attached, without the use of a CAN signal. In particular, the problem addressed by the invention is that of providing a method, which can be used independently of a system or independently of a vehicle.